Rep. Gabrielle Giffords’ condition has been upgraded from critical to serious, reflecting the removal of a ventilator that had assisted in her breathing since she was shot in the head eight days ago.

“The congresswoman continues to do well,” the University of Arizona Medical Center reported in a Sunday statement. “She is breathing on her own. Yesterday’s procedures were successful and uneventful.”

On Saturday, the third-term Arizona Democrat underwent tracheotomy surgery to open her windpipe and had a feeding tube inserted.

The past week has brought a steady stream of positive signs for Giffords: an early ability to hold up two fingers; giving a thumbs-up signal; opening her eyes when she was visited by three colleagues midweek; removing and replacing her husband’s wedding ring; and now the upgrade of her condition.

She was shot by a would-be assassin outside a Tucson supermarket in a rampage that killed six people. The suspect in the shootings, Jared Lee Loughner, is due in court Jan. 24.